1. Prof Afonso Ferreira Miguel
USART 8051
Prof Afonso Ferreira Miguel

2. Microcontrolador 8051 (MCS-51) Interface Serial
Full duplex UART.
Four modes of operation:
Synchronous serial I/O expansion.
Asynchronous serial I/O with variable baud rate.
Nine bit mode with variable baud rate.
Nine bit mode with fixed baud rate.
10 or 11 bit frames.
Interrupt driven or polled operation.
Registers:
SCON - Serial port control register.
SBUF - Read received data.
- Write data to be transmitted.
PCON - SMOD bit.

3. Microcontrolador 8051 (MCS-51) Interface Serial: Modos
TXD and RXD are the serial output and input pins (Port 3, bits 1 and 0).
Mode 0: Shift Register Mode. Serial data is transmitted/received on RXD. TXD outputs shift clock. Baud Rate is 1/12 of clock frequency;
Mode 1: 10-bits transmitted or received. Start (0), 8 data bits (LSB first), and a stop bit (1). Baud Rate Clock is variable using Timer 1 overflow or external count input. Can go up to 104.2KHz (20MHz osc.);
Mode 2: 11-bits transmitted or received. Start (0), 8 data bits (LSB first), programmable 9th bit, and stop bit (1). Baud Rate programmable to either 1/32 or 1/64 oscillator frequency (625KHz for 20MHz osc.);
Mode 3: 11-bit mode. 9 data bits; Baud Rate variable using Timer 1 overflow or external input KHz max. (20 MHz osc.).

4. Microcontrolador 8051 (MCS-51)
SCON

5. Microcontrolador 8051 (MCS-51)

6. Microcontrolador 8051 (MCS-51)
Configuração

7. Microcontrolador 8051 (MCS-51)
Rotinas típicas para TX e RX um byte

8. Microcontrolador 8051 (MCS-51)
Rotina típica para transmitir uma string

9. Microcontrolador 8051 (MCS-51)
Utilizando a rotina anterior:
Definindo a string em memória